CN107699833B - Plating assistant additive, plating assistant liquid and hot dipping method - Google Patents
Plating assistant additive, plating assistant liquid and hot dipping method Download PDFInfo
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- CN107699833B CN107699833B CN201710703344.2A CN201710703344A CN107699833B CN 107699833 B CN107699833 B CN 107699833B CN 201710703344 A CN201710703344 A CN 201710703344A CN 107699833 B CN107699833 B CN 107699833B
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C215/00—Compounds containing amino and hydroxy groups bound to the same carbon skeleton
- C07C215/02—Compounds containing amino and hydroxy groups bound to the same carbon skeleton having hydroxy groups and amino groups bound to acyclic carbon atoms of the same carbon skeleton
- C07C215/40—Compounds containing amino and hydroxy groups bound to the same carbon skeleton having hydroxy groups and amino groups bound to acyclic carbon atoms of the same carbon skeleton with quaternised nitrogen atoms bound to carbon atoms of the carbon skeleton
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
- C23C2/36—Elongated material
- C23C2/38—Wires; Tubes
Abstract
The invention relates to an additive for plating assistant, a plating assistant solution and a hot dipping method in the technical field of chemical industry, wherein the additive for plating assistant contains a compound shown as the following formula I:
Description
Disclosure of Invention
The invention belongs to the technical field of chemical industry, and particularly relates to an additive for plating assistant, a plating assistant solution and a hot dipping method.
Background
The surface of the metal material is coated with other metal or nonmetal protective layers, so that the corrosion of the base metal material can be effectively prevented. The hot-dip plating technology, including hot-dip galvanizing, hot-dip galvanizing aluminium alloy and hot-dip aluminizing, mostly adopts solvent method, and its principle is that the workpiece is immersed in the molten metal to be galvanized, and the workpiece is taken out, and after cooled, its surface is covered with a thin plating layer, so that its corrosion resistance can be greatly raised, and can save material and resource, and can give play to good economic benefit and environmental benefit. The quality of the coating directly affects the corrosion resistance, so that the workpiece is subjected to strict processes of degreasing, rinsing, pickling, rinsing, plating aid, drying and the like before being immersed in the molten metal to be plated.
The plating assistant procedure is a necessary and important link in the hot-dip plating metal process. Plating assistant is a process of immersing the degreased workpiece into a plating assistant agent solution, taking out the workpiece and forming a continuous plating assistant salt film on the surface of the workpiece, and drying is to remove the moisture on the surface of the workpiece and keep the salt film. The quality of the plating assistant effect directly influences the plating quality indexes such as plating uniformity, continuity, adhesion strength, brightness, smoothness and the like, and also influences the time and effect of the subsequent drying process, thereby influencing the production efficiency, plating metal consumption and operation environment. The plating assistant process and the plating assistant agent have a direct relation to the improvement of the plating assistant effect.
The plating assistant solution needs to be added with additives to enhance the plating assistant effect. The additive can greatly improve the adhesion uniformity of the plating solution and greatly reduce the plating leakage; the interface wettability between the liquid coating metal and the workpiece is better; the plating assistant agent adhesion uniformity and continuity are improved, plating leakage is prevented, meanwhile, the plating assistant agent adhesion amount can be reduced, and the plating assistant agent consumption is reduced; after the workpiece is immersed in the plating assistant solution, a special hydrophobic film is formed on the surface of the workpiece, so that the drying time of the plating assistant agent is greatly shortened, and the production efficiency is improved; the zinc liquid splashing strength is weakened, the accident risk such as scalding is reduced, and the working environment of workers is improved; the zinc dipping time is shortened, the zinc coating is thinned, and the consumption of the coating material is further reduced; the residue form is improved, the ash content is reduced, and the ash discharging speed is increased; the residual oxygen on the surface of the plated part is thoroughly removed, air is isolated, and oxidation is avoided; decomposing to generate reducing gas, protecting the plated part and dispersing residual dirt; the surface coating of the plated part is brighter and smoother, and the adhesiveness is stronger.
The additive usually contains special surface active components, has extremely strong penetration and wetting capabilities, can form a continuous uniform thin layer on the surface of a plated part, greatly reduces the surface tension of the plating solution, and greatly improves the wettability of the plating solution and the surface of the plated part. The selection and the proportion of the additive play an important role in realizing the plating assistant effect, and the additive obtained by selecting and proportioning different components has great difference in improving the plating assistant effect. However, the additives already disclosed in the prior art still have a certain technical effect.
Disclosure of Invention
The invention relates to an additive for plating assistant, a plating assistant solution and a hot dipping method. The preparation and use methods of the additive are very simple, the biodegradability is good, the additive does not cause damage to the environment and related operators, and the additive is suitable for hot galvanizing, hot galvanizing aluminum alloy, hot aluminizing and other processes.
The invention is realized by the following technical scheme,
in a first aspect, the present invention relates to an additive for fluxing comprising a compound of formula I:
wherein R1 is C12-16 alkyl; r2 is methyl or hydroxypropyl; r3 is one of hydroxyethyl, hydroxypropyl and dihydroxypropyl; r4 is one of methyl, hydroxyethyl and dihydroxypropyl, and X is one of Cl, Br and I.
Preferably, in the compound of formula (I), R1 is C12 alkyl, R2 is methyl, R4 is methyl, R3 is dihydroxypropyl, and X is Cl; namely dodecyl dimethyl (2, 3-propanediol based) ammonium chloride.
Preferably, in the compound of formula (I), R1 is C14 alkyl, R2 is methyl, R4 is methyl, R3 is dihydroxypropyl, and X is Cl; namely tetradecyldimethyl (2, 3-propanediol-based) ammonium chloride.
Preferably, in the compound of formula (I), R1 is C12 alkyl, R2 is methyl, R4 is methyl, R3 is hydroxyethyl, and X is Cl; namely dodecyl dimethyl hydroxyethyl ammonium chloride.
Preferably, in the compound of formula (I), R1 is C12 alkyl, R2 is methyl, R4 is hydroxyethyl, R3 is hydroxyethyl, and X is Cl; namely dodecyl bis hydroxyethyl methyl ammonium chloride.
Preferably, in the compound of formula (I), R1 is C12-14 alkyl.
Preferably, the additive also comprises a compound shown as a formula II,
and
wherein R1' is one of C8-18 long-chain alkyl amidopropyl and C12-18 alkyl; r2' is methyl or hydroxyethyl; r4' is methyl or hydroxyethyl; r3' is propyl sulfo, hydroxypropyl sulfo, propyl carboxy or hydroxypropyl carboxy.
Preferably, in the compound formula (II), R1 'is C12 long-chain alkyl amidopropyl, R2' is methyl, R4 'is methyl, and R3' is hydroxypropyl sulfo;
namely, it is
Preferably, in the compound of formula (ii), R1 'is C12 alkyl, R2' is methyl, R4 'is methyl, and R3' is propylsulfo;
namely, it is
In a second aspect, the present invention also relates to a plating assistant solution, which contains the aforementioned additive.
In a third aspect, the invention further relates to a preparation method of the plating assistant solution, which comprises the following steps: adding water into the plating assistant tank, then adding zinc chloride, ammonium chloride and additives, dissolving and heating to obtain the zinc-ammonium-zinc alloy.
Preferably, the mass of zinc chloride added per liter of water is 110-120 g.
Preferably, the mass of ammonium chloride added per litre of water is 150-160 g.
Preferably, the content of the additive in the plating assistant solution is 0.8-1%, and the percentage is mass percentage.
The invention also relates to a hot dip coating method, which comprises the following steps: taking a steel pipe fitting, sequentially carrying out acid pickling and water washing, and then putting the steel pipe fitting into the plating assistant solution for plating assistant; and taking out the steel pipe fitting, placing, and then immersing into a high-temperature liquid metal bath for hot dip coating.
Compared with the prior art, the invention has the following beneficial effects:
the additive for the hot dip plating assistant agent realizes unexpected good technical effects; the additive is used for preparing the plating assistant solution to carry out the treatment of the plating assistant process, so that the molten plating metal and the workpiece have better interface wettability; the plating-assistant agent attachment amount is reduced while the occurrence of plating leakage is prevented; the secondary oxidation of the workpiece is prevented; the drying process is greatly accelerated, the production efficiency is improved, and meanwhile, the residual moisture on the surface of the workpiece is avoided, so that the liquid metal waterfall is eliminated, the accident risks such as scalding are greatly reduced, and the raw materials are saved; the dip plating time is shortened, the plating layer is thinned, and the material consumption is further reduced; further removing residual oxide impurities on the surface of the workpiece, further improving the ash form, reducing the generation of ash and improving the ash discharging speed; the plating layer is brighter and smoother, and the adhesiveness is stronger. The preparation and use methods of the additive are very simple, the biodegradability is good, the additive does not cause damage to the environment and related operators, and the additive is suitable for hot galvanizing, hot galvanizing aluminum alloy, hot aluminizing and other processes.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.
Examples 1 to 14
In order to verify the effect of the additive, the applicant respectively carries out experimental verification, and the experimental contents are as follows:
firstly, analyzing the plating assisting effect;
preparing a plating assistant solution;
adding water into the plating assistant tank, then adding zinc chloride and ammonium chloride and additives (if any) according to the proportion that 110-. Taking a Q235 steel sheet with the same specification of 5cm x 10cm x 0.3cm, sequentially carrying out acid pickling and water washing, drying, weighing, and immersing in different plating assistant solutions for 20 minutes.
And taking out, observing the surface moisture drying condition, and recording the drying time. After the moisture is dried, weighing and calculating the adhesion amount of the plating assistant agent salt film, and observing the state of the salt film. The experiment examined the following criteria: 1. drying time; 2. the amount of adhesion; 3. drying to obtain salt film. In the plating assisting procedure, the drying time of the workpiece directly influences the plating assisting efficiency, the short drying time ensures that the immersion plating waiting time of the workpiece after plating assisting is short, and liquid metal waterfall caused by residual moisture in the immersion plating process can be avoided; the adhesion amount and the morphology of the salt film directly influence the thickness and the quality of the plating layer.
(II) the additives used in the different schemes are described below;
1. no additives were added in scheme 1.
2. The additive of the combination G is added into the scheme 2, and the addition amount is 0.8-1% (w/w).
The composition of the combination G additive is as follows (component 1, component 2, component 3 in a molar ratio of 2:1: 1):
| component 1 | C12H25N(CH3)2CH2CH2SO3 |
| Component 2 | C12H25N(CH2C6H5)(CH3)2Br |
| Component 3 | (C8H17)2N(CH3)2Br |
3. The additive added in the scheme 3 is the cationic surfactant related to the invention, and the addition amount is 0.8-1% (w/w).
4. The additive added in the scheme 4 is the amphoteric surfactant related to the invention, and the addition amount is 0.8-1% (w/w).
5. The additive added in the scheme 5 is the compound of the cationic surfactant and the amphoteric surfactant, the addition amount of the two surfactants is 0.8-1% (w/w) in total, and the two surfactants are used according to the dosage after being compounded in advance.
TABLE 1 example set-up
TABLE 2 analysis of plating assistant effect
Table 2 shows the results of the effect analysis in table 2:
1. and (4) drying time. As can be seen from table 2, the average drying time for protocol 1 was 7.8 minutes. The additive was used in each of the schemes 2,3, 4 and 5, and it can be seen from the results that the drying time using the additive was greatly shortened, and in terms of the specific shortening, the average time of the scheme 2 was 3.3 minutes, the average time of the scheme 3 was 2.48 minutes, the average time of the scheme 4 was 3.06 minutes, and the average time of the scheme 5 was 1.95 minutes; it can be seen that, in terms of the degree of shortening of the drying time, scheme 5> scheme 3> scheme 4> scheme 2. It is noteworthy that in scheme 3, the drying times for examples 1-4 were all below 3 minutes, significantly better than the other examples in scheme 3.
2. And (5) analyzing the attached quantity. It can be seen that after the additive is used, the salt film obtained after the steel sheet is subjected to hot dip coating has good quality, and the adhesion amount of the salt film is reasonably and greatly reduced. As can be seen, the average amount of adhesion for case 1 is 43.9g, case 2 is 26.4g, case 3 is 24.6g, case 4 is 25.1g, case 5 is 23.8 g. It can be seen that, in terms of the effects of the adhesion amount, the case 5> the case 3> the case 4> the case 2.
Therefore, the additive provided by the invention can be used for remarkably shortening the drying time of a workpiece while improving the quality of a coating, the drying time after the additive is adopted is shortened by 70-80% compared with the time without the additive, the drying time is remarkably accelerated, the production effect is greatly improved, the problems of zinc ash, smoke and the like generated in the galvanizing process can be remarkably reduced, the risk of liquid immersion plating cascade splashing is greatly reduced, and unexpected technical effects are realized.
Secondly, analyzing the field production effect;
a production method;
preparing a plating assistant solution: adding water into the plating assistant tank, then adding zinc chloride and ammonium chloride according to the proportion of adding 120g of zinc chloride in 110-.
DN200 steel pipe fittings are taken, washed by hydrochloric acid (30 minutes) of 20 percent (volume fraction) and water in sequence, and then immersed in the plating assistant solution at 60 ℃ for 5 minutes.
Taking out the steel pipe fitting from the plating assistant solution, staying in the air for 2-3 minutes, then immersing into a high-temperature liquid metal bath for dip plating for 2-3 minutes (performing ash scraping and part lifting processes), then taking out the steel pipe fitting, and respectively inspecting related indexes: 1. liquid metal splash strength 2, coating surface quality: spangles are uniform in size, free of defects (plating leakage, beading or burrs), bright and smooth.
The hot galvanizing is taken as an example in the field production experiment, and the coating quality is inspected according to the method in GB/T13912 and 2002 metal covering steel part hot dip galvanizing coating technical requirements and test methods.
TABLE 3 field production Effect analysis
In the field experiment, DN200 steel pipe fittings (Q235 steel) are taken, plating assisting and dip plating are carried out in sequence, and the results are as follows through data statistics and apparent detection: taking the comparison scheme 1, the comparison scheme 2 and the DN200 steel pipe fitting (the wall thickness is 6mm) obtained by the scheme assistant plating, measuring the plating thickness of each group of plating parts on site, and basically exceeding the minimum value of 85 μm by the average plating thickness according to the requirements of GB/T13912 and 2002 standards.
And analyzing the thickness deviation of the coating. It can be seen that there are significant differences between the schemes. And (4) carrying out single-point coating thickness measurement, and selecting 5 points for each steel pipe fitting to carry out coating thickness measurement. The applicant found that the maximum deviation of the plating thickness of comparative example 1 was 10.7 μm on average, that of example 2 was 4.1 μm, that of example 3 was 2.45 μm, that of example 4 was 3.14 μm, and that of example 5 was 1.2 μm, and found that, in terms of the superior and inferior effects of the uniformity of the plating thickness, example 5> example 3> example 4> example 2> example 1. For analysis reasons, the additive plating assisting effect has very important influence on the formation of the salt film, and the worse plating assisting effect, the more uneven the salt film on the surface of the dried workpiece is, and further the deviation of the plating layer on the surface of the workpiece is larger.
The applicant observes that the coating appearance of the workpiece treated by the comparative scheme has the following problems: and (4) missing plating, the surface of the plating layer is rough, the surface of the plating layer has more burrs, and the surface of the plating layer has the quality problems of droppings and the like. The single plating-through area of the surface of each workpiece even exceeds 10cm2There is a serious quality problem and rework repair is necessary if it is used. And the reworking repair needs acid pickling and zinc removal, and then re-plating and dip plating are assisted, so that the serious waste of resources is caused, and the production cost of enterprises is greatly increased.
Thirdly, the mechanism of the invention is explained;
from the foregoing experimental results, it can be seen that the plating assistant effect can be significantly improved by using the additive of the present invention, and for these significant effects, the applicant elaborates as follows:
the cationic surfactant of the present inventionThe general formula is:
wherein R1 is C12-16 alkyl; r2 is methyl or hydroxypropyl; r3 is one of hydroxyethyl, hydroxypropyl and dihydroxypropyl; r4 is one of methyl, hydroxyethyl and dihydroxypropyl, and X is one of Cl, Br and I;
the person skilled in the art knows that for the additive, the choice of the structural formula and the choice of the functional groups in the structural formula have a decisive influence on the properties of the additive. For the additive, the formula of the surfactant is chosen taking into account both properties:
1. the water solubility of the surfactant needs to be moderate. For the additives, the surfactant needs to be capable of self-dissolving in an aqueous or electrolyte solution, but at the same time not to have too high a water solubility; therefore, the HLB value of the surfactant must be selected to be moderate; 2. the surface active agent needs to have moderate electro-adsorption performance. The functional group connected with the central N atom in the structural formula of the surfactant keeps balance on the electron donating effect and the electron withdrawing effect of the central charged atom; when the functional group of the structural formula is selected, the influence of the functional group on the HLB value of the whole structural formula and the influence on the charge performance of the central atom of the structural formula are considered, so that the adsorption capacity of the whole structural formula in an aqueous solution can meet the requirement of the additive. In the application process of the cationic surfactant, the force attached to the metal surface mainly depends on electrostatic adsorption, namely, the positive charge carried by the central N atom interacts with the negative charge on the metal surface.
The water solubility of the structural formula is related to the functional group, and if the hydrophilic property of the functional group is good, the water solubility of the structural formula is greatly improved; however, if the molecular weight of the functional group is larger or increased with the increase of the functional group, the adsorbability of the structural formula is lowered.
For surfactants, consideration of both water solubility and electroabsorption properties is required, and the best results are achieved only if the requirements of both of these criteria are met. For the additive, the choice of functional group in the structural formula of the surfactant is very important, directly affecting the water solubility and the electroadsorption properties:
1. in combination with the structural formula of the invention, the structural formula R1 selects the alkyl with the carbon number of 12-16, and the structural formula of the invention can select branched chain or straight chain fatty amine, but when the straight chain alkyl is selected, the structural formula has more excellent effect. This is because, when the structural formula of the present invention selects a branched long-chain alkyl group, when the surfactant is attached to a metal surface, the attachment density of the surfactant is reduced due to the steric hindrance effect of the branch chain, so that a monomolecular layer formed by the surfactant is loose and weak, and the hydrophobic protection of the surfactant on the metal surface is reduced.
Preferably, R1 in the structural formula of the invention selects C12-C14 straight carbon chain alkyl; because the more carbon numbers of R1, the steric hindrance effect generated by R1 and R2, R3 and R4 is increased, and the attachment density of the surfactant is reduced, so that a monomolecular layer formed by the surfactant is loose and not firm, and the hydrophobic protection of the surfactant on a metal surface is reduced. If the number of carbon atoms in R1 is too small, selection of R2, R3 and R4 is not favorable, and the performance of the overall structural formula cannot be satisfied. Thus, an appropriate carbon number chain for R1 must be selected.
2. For the structural formula of the invention, wherein the selection of R2, R3 and R4 is crucial, the combination of different selection compositions of R2, R3 and R4 can have important influence on the charge adsorption property and HLB value of the surfactant.
The selective combination of R2, R3 and R4 groups has important influence on the charge adsorption property and HLB value of the surfactant; the R2, R3 and R4 groups are selected taking into account the following factors:
(1) the selection of the group has smaller influence on the charge adsorption of the central N atom of the structural formula, so that the charge property of the whole structural formula is prevented from being reduced;
(2) the steric hindrance of the group should be small so as to avoid reducing the adsorption capacity of the N atom on the metal surface and to facilitate the dissolution of the long carbon chain structure;
(3) the hydrophobicity of the group is reduced as much as possible to avoid reducing the HLB value of the structural formula;
(4) the selective combination of the R2, the R3 and the R4 groups also reduces the steric hindrance effect formed with the R1 as much as possible on the whole, increases the attachment density of the surfactant as much as possible, ensures that a monomolecular layer formed by the surfactant is firmer, and enhances the hydrophobic protection of the surfactant on the metal surface.
The applicant's research has surprisingly found that the combination of R1, R2, R3 and R4 has unexpected technical effects when selected as follows, and the specific combination is as follows:
the general formula of the cationic surfactant is as follows:
TABLE 5
| Combination of | R1 | R2 | R3 | R4 | X |
| 1 | Alkyl of C12 | Methyl radical | Dihydroxypropyl radical | Methyl radical | Cl |
| 2 | Alkyl of C14 | Methyl radical | Dihydroxypropyl radical | Methyl radical | Cl |
| 3 | Alkyl of C12 | Methyl radical | Hydroxyethyl group | Methyl radical | Cl |
| 4 | Alkyl of C12 | Methyl radical | Hydroxyethyl group | Hydroxyethyl group | Cl |
Through a large number of experiments, the applicant unexpectedly finds that the combination of the four groups R1-R4 recorded in the combinations 1-4 can realize the optimal effect of the structural formula on the charge property of the whole structural formula, the overall steric hindrance response, the HLB value of the structural formula and other factors, so that the attachment density of the surfactant corresponding to the structural formula is remarkably increased, a monomolecular layer formed by the surfactant is particularly firm, and the hydrophobic protection capability of the surfactant on the metal surface is remarkably enhanced. The applicant simultaneously found that if the combination of R1, R2, R3 and R4 is adjusted, the ingenious combination realized by the structural species R1, R2, R3 and R4 is broken to a certain extent, and the direct result is that the solubility of the expression active agent corresponding to the structural formula is greatly reduced, and the use effect is reduced, and from the analysis of the plating assistant effect in table 2 and the analysis of the on-site production effect in table 3, it can be seen that scheme 3 includes examples 1 to 6, wherein examples 1 to 4 are compounds corresponding to the combination listed in table 5, and examples 5 to 6 are not taken from the above combination, and it can be seen that the plating assistant effect and the on-site production effect in examples 1 to 4 are significantly better than those in examples 5 and 6, and have unexpected technical effects.
Further, the applicant found that if the cationic surfactant represented by formula i and the amphoteric surfactant are compounded, the effect of the plating assistant additive can be further improved, and as described in examples 12 to 15, the compounding can not only reduce the usage amount of the additive, but also exhibit a synergistic effect, and the plating assistant additive exhibits a more excellent effect than the cationic surfactant or the amphoteric surfactant alone. The reason for this was analyzed as follows: for a built-up additive consisting of a plurality of components, the selection of the components has a decisive influence on the effect of the built-up additive. In the compounding process, different ionic surfactants usually precipitate or generate flocculent complexes, so that the effect of the compounding additive is influenced, and even the surface activity of the compounding additive is lost. The reason why the precipitation or the flocculent complex is generated is that different ionic surfactants have different structural formulas and characteristics, and the structural formula molecules act with each other.
However, if the structural formulas of different surfactants are carefully considered, the functional groups in the surfactants are specially selected and effectively designed, so that the negative effects generated among different ionic surfactants can be effectively avoided, and conversely, the synergistic effect of different ionic surfactants can be realized, so that the effect of the compound additive is superior to the effect of using a single additive alone, and the compound additive system has very high surface activity and shows very strong synergistic effect.
The cationic surfactant and the amphoteric surfactant according to the present invention have excellent effects when used alone. The inventor of the invention compounds the cationic surfactant and the amphoteric surfactant, and unexpectedly finds that the compounded additive realizes very obvious synergistic action. For this reason, the applicants believe that the anionic groups of the two surfactants interact with each other to achieve a synergistic effect.
In the compound additive, functional groups in the cationic surfactant and the amphoteric surfactant interact with each other to generate electrostatic adsorption, and hydrophobic interaction between the functional groups enables surfactant molecules in the solution to be more easily aggregated to form a micelle, so that the surfactant molecules in the surface adsorption layer are more closely arranged and have lower surface energy, and the surface adsorption capacity is greatly increased. The surface activity is greatly improved because the anionic-cationic surfactants are compounded together to generate strong electric action with each other. Compared with a single surfactant, the surface tension of the solution can be greatly reduced (the number of carbon chains of two ionic surfactants is equal) by adding a small amount of counter-ionic surfactant into the cationic (anionic) surfactant, the surface tension reaches the lowest value at a certain mass ratio, and the CMC is reduced to be less than that of the single surfactant solution.
The structural formula of the compounded amphoteric surfactant is as follows:
wherein R1/is one of long-chain alkyl amidopropyl of C8-18 and C12-18 alkyl; r2/, R4/, methyl, hydroxyethyl; r3/is propyl sulfo, hydroxypropyl sulfo, propyl carboxyl or hydroxypropyl carboxyl.
The structural formula selected by the invention has specificity, contains strong basic N atoms which are N atoms in quaternary ammonium groups to form a betaine structure, and has univalent positive charges irrelevant to pH in a wider pH range. The structural formula of the invention has the structural characteristics that the compound can simultaneously have the capacity of releasing one proton and absorbing one proton in a solution. While the "zwitterionic" surfactants containing strongly basic N atoms exhibit two other distinct ion exchange characteristics, as described in detail below: in the structural formula of the invention, R3 is propyl sulfo, hydroxypropyl sulfo, propyl carboxyl or hydroxypropyl carboxyl, namely carboxylic acid type betaine and sulfo type betaine. In the case of the carboxybetaine surfactant, where R3 is a propyl or hydroxypropyl carboxyl group, in strongly acidic solutions the negatively charged central carrier carboxyl group is likely to accept a proton to form the cationic form, but in strongly basic solutions the positively charged central carrier quaternary ammonium N is unlikely to lose a proton to form the anionic form, thus sharing the presence of both ionic forms. In the case of the sulfobetaine surfactant, R3 in the formula is a propyl sulfo group or a hydroxypropyl sulfo group, does not exhibit the ability to accept protons or release protons in almost all pH ranges, and is always present in the form of an ionic inner salt, and thus is a true amphoteric surfactant. In the structural formula, R2 and R4 can be selected from a plurality of groups generally, but the best technical effect of the invention can be realized only when methyl is selected from a plurality of groups by combining the special application medium environment and the compounding synergistic effect of other surfactants. In the structural formula of the invention, R1 can be selected from long-chain alkyl amidopropyl of C8-18 or C12-18 alkyl, and like quaternary ammonium salt cationic surfactants, the hydrophobicity after adsorption in an application medium environment needs to be considered. Because the zwitterionic surfactant contains both anionic and cationic groups, its solubility is less limited by the electrolyte and pH range, or even less affected than that of the nonionic surfactant. While those containing weakly basic nitrogen exhibit minimal solubility near their isoelectric point due to interaction between the ionized groups. In general, the hydrophilicity of an amphoteric surfactant is critically dependent on the water solubility of its anionic groups, e.g., an anionic group such as a carboxylic acid group, etc. is effective in solubilizing a carbon-hydrogen chain containing twelve carbon atoms; two protonated nitrogen-containing cationic groups are effective in solubilizing one hydrocarbon chain containing eighteen carbon atoms. In the invention, through a great deal of research, the applicant finds that the special technical effect can be realized by compounding the selected combination of R1, R2, R3 and R4 with the cationic surface activity related to the invention, specifically, in the structural formula II of the invention, R1 'is C12 long-chain alkyl amidopropyl, R2' is methyl, R4 'is methyl, and R3' is hydroxypropyl sulfo; or R1 'is C12 alkyl, R2' is methyl, R4 'is methyl, and R3' is propylsulfo. The applicant has found that in the structural formula II of the present invention, R1, R2, R3 and R4 are synergistic with each other, and the four groups can achieve an unexpected synergistic technical effect only when the two forms are combined, if one of the four groups is adjusted, the performance of the structural formula is greatly reduced, for example, R3 'selects no hydroxypropyl sulfo or propyl sulfo but selects anionic groups such as propyl carboxyl or hydroxypropyl carboxyl, R1' selects no C12 long-chain alkyl amidopropyl group but selects a C8 or C18 long-chain alkyl amidopropyl group, and the performance of the structural formula is greatly reduced.
In conclusion, the additive for the hot dip plating assistant agent realizes unexpected good technical effects; the additive is used for preparing the plating assistant solution to carry out the treatment of the plating assistant process, so that the molten plating metal and the workpiece have better interface wettability; the plating-assistant agent attachment amount is reduced while the occurrence of plating leakage is prevented; the secondary oxidation of the workpiece is prevented; the drying process is greatly accelerated, the production efficiency is improved, and meanwhile, the residual moisture on the surface of the workpiece is avoided, so that the liquid metal waterfall is eliminated, the accident risks such as scalding are greatly reduced, and the raw materials are saved; the dip plating time is shortened, the plating layer is thinned, and the material consumption is further reduced; further removing residual oxide impurities on the surface of the workpiece, further improving the ash form, reducing the generation of ash and improving the ash discharging speed; the plating layer is brighter and smoother, and the adhesiveness is stronger. The preparation and use methods of the additive are very simple, the biodegradability is good, the additive does not cause damage to the environment and related operators, and the additive is suitable for hot galvanizing, hot galvanizing aluminum alloy, hot aluminizing and other processes.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.
Claims (10)
1. An additive for assisting in plating, the additive comprising a compound of formula I:
wherein the content of the first and second substances,
in the compound shown in the formula (I), R1 is C12 alkyl, R2 is methyl, R4 is methyl, R3 is hydroxyethyl, and X is Cl; namely dodecyl dimethyl hydroxyethyl ammonium chloride;
the additive also comprises a compound shown as a formula II, and
in the compound formula (II), R1 'is a C12 long-chain alkyl amidopropyl group, R2' is a methyl group, R4 'is a methyl group, and R3' is a hydroxypropyl sulfo group;
namely, it is
2. An additive for assisting in plating, the additive comprising a compound of formula I:
r1 is C12 alkyl, R2 is methyl, R4 is methyl, R3 is dihydroxypropyl, and X is Cl; namely dodecyl dimethyl (2, 3-propanediol based) ammonium chloride;
the additive also comprises a compound shown as a formula II, and
in the compound formula (II), R1 'is a C12 long-chain alkyl amidopropyl group, R2' is a methyl group, R4 'is a methyl group, and R3' is a hydroxypropyl sulfo group;
namely, it is
3. An additive for assisting in plating, the additive comprising a compound of formula I:
in the compound shown in the formula (I), R1 is C14 alkyl, R2 is methyl, R4 is methyl, R3 is dihydroxypropyl, and X is Cl; tetradecyldimethyl (2, 3-propanediol-based) ammonium chloride
The additive also comprises a compound shown as a formula II, and
in the compound shown in the formula (II), R1 'is C12 alkyl, R2' is methyl, R4 'is methyl, and R3' is propylsulfo; namely, it is
4. An additive for assisting in plating, the additive comprising a compound of formula I:
in the compound shown in the formula (I), R1 is C12 alkyl, R2 is methyl, R4 is hydroxyethyl, R3 is hydroxyethyl, and X is Cl; namely dodecyl bis hydroxyethyl methyl ammonium chloride;
the additive also comprises a compound shown as a formula II, and
in the compound shown in the formula (II), R1 'is C12 alkyl, R2' is methyl, R4 'is methyl, and R3' is propylsulfo; namely, it is
5. A plating assistant solution, characterized in that the plating assistant solution contains the additive according to any one of claims 1 to 4.
6. The method for preparing the plating assistant solution according to claim 5, comprising the following steps: adding water into a plating assistant tank, then adding zinc chloride, ammonium chloride and the additive as claimed in any one of claims 1-4, dissolving and heating to obtain the zinc-zinc.
7. The method according to claim 6, wherein the amount of zinc chloride added per liter of water is about 110-120 g.
8. The method according to claim 6, wherein the mass of ammonium chloride added per liter of water is 150-160 g.
9. The method according to claim 6, wherein the additive is contained in the plating assistant solution in an amount of 0.8 to 1% by mass.
10. A hot dip coating method, characterized by comprising the steps of:
taking a steel pipe fitting, sequentially carrying out acid pickling and water washing, and then putting the steel pipe fitting into the plating assistant solution according to claim 5 for plating assistant;
and taking out the steel pipe fitting, placing, and then immersing into a high-temperature liquid metal bath for hot dip coating.
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| CN115354255B (en) * | 2022-07-12 | 2024-02-02 | 江苏甬金金属科技有限公司 | Stainless steel strip with hot-dip zinc-aluminum alloy coating and preparation method thereof |
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| CN1117344A (en) * | 1994-06-08 | 1996-02-28 | 罗姆和哈斯公司 | Low leaching compositions for wood |
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| CN105908113A (en) * | 2016-05-06 | 2016-08-31 | 长安大学 | Plating assistant agent for zinc-aluminum-nickel-rare earth-alloy hot-dip plating and technological method |
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| CN1117344A (en) * | 1994-06-08 | 1996-02-28 | 罗姆和哈斯公司 | Low leaching compositions for wood |
| CN1196927A (en) * | 1997-03-06 | 1998-10-28 | 庄臣及庄臣有限公司 | Chemical composition |
| CN101122000A (en) * | 2007-09-21 | 2008-02-13 | 王玉强 | Phytate plating resisting agent for heat zinc coating |
| CN101328568A (en) * | 2008-06-23 | 2008-12-24 | 南通飞拓生物科技有限公司 | Multifunctional assistant plating additive for hot dip plating process, preparation and use method thereof |
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